Plasma processing method

Abstract

In a plasma processing method, a silicon layer of an object to be processed is etched by using a plasma of a processing gas introduced into an airtight processing chamber through a patterned mask. The processing gas contains a gaseous mixture of HBr, O 2 and SiF 4 and, additionally, one or both of SF 6 gas and NF 3 gas; and a gas containing C and F is further added to the processing gas.

What is claimed is:  
     
         1 . A plasma processing method comprising the step of: 
 etching a silicon layer of an object to be processed by employing a patterned mask and by using a plasma of a processing gas introduced into an airtight processing chamber, containing a gaseous mixture of HBr, O 2  and SiF 4  and, additionally, one or both of SF 6  and NF 3 ,    wherein a gas containing C and F is further added to the processing gas.    
     
     
         2 . The plasma processing method of  claim 1 , wherein the gas containing C and F is one or more gases selected from the group consisting of CF 4 , C 4 F 8 , C 5 F 8 , C 4 F 6 , CHF 3  and CH 2 F 2 .  
     
     
         3 . The plasma processing method of  claim 1 , wherein the gas containing C and F is added to the processing gas in a middle of the etching step.  
     
     
         4 . The plasma processing method of  claim 3 , wherein the gas containing C and F is continuously added to the processing gas until the end of the etching step.  
     
     
         5 . The plasma processing method of  claim 1 , wherein the gas containing C and F is added to the processing gas for a period of time during the etching step.  
     
     
         6 . The plasma processing method of  claim 1 , wherein the timing of starting to add the gas containing C and F to the processing gas is determined according to the opening diameter of holes or the opening width of grooves formed by the etching step.  
     
     
         7 . The plasma processing method of  claim 1 , wherein the opening diameter of holes or the opening width of grooves formed by the etching step is smaller than or equal to about 0.2 μm.  
     
     
         8 . The plasma processing method of  claim 1 , wherein the patterned mask includes at least an oxide layer containing silicon.